: Although there has been a great deal of research on risk taking behavior, there remains a need for a better understanding of the underlying factors leading to the expression of such behavior. For example, it would be useful to know the underlying genetic precursors and personality types that are more likely to lead to risk taking behavior and some of the more enduring protective factors that also exist. Researchers and clinicians could then identify and attempt to intervene with those at increased risk for experiencing the adverse outcomes normally associated with risk taking behavior, including incarceration, substance abuse problems, and contracting and transmitting sexually transmitted diseases. This study aims to address these issues by identifying personality types and genetic precursors that increase an individual?s risk for, and factors that may protect an individual from, the development of risk taking behavior. In this study, it is hypothesized that genetic transmission plays a role in the development of sensation seeking, which is advanced as a personality factor that may lead to risk taking behavior. Additionally, apprehension (i.e., trait anxiety) is advanced as a protective factor that may aid in keeping individuals from developing risk taking behavior. One goal of this study is to develop better measures of a sensation seeking attitude than are currently available. A second goal is to examine whether apprehension moderates the relationship between sensation seeking attitude and risk taking behavior. A third goal is to identify genetic precursors of sensation seeking and risk taking behavior. Finally, this research will attempt to examine possible intervention strategies using this knowledge to aid in identifying individuals at risk.